In this study, we have initiated a three-dimensional reconstruction of microtubule nucleation centers of the erythrophrus of Holocentrus as viewed by high voltage electron micrographs. So far, we have measured the functional volume, surface area, and pore size of the mictrotubecular lattice and the cytoskeleton of cells and found that they occupy only a relatively small volume of the cytoplasm, contrary to what was intuitively assumed before. These results were correlated with recent measurements of diffusion of molecules throughout the cytoplasm. In addition we have begun to construct a stereo-image analysis system that includes color graphics. This system will be used to study the three-dimensional structure of cells and their biological functions.